Hampton Roads continues to see rising tides linked to climate change and sinking land.
But the rate of change in recent years has stayed in line with past forecasts, according to the latest “sea level rise report card” from William & Mary’s Batten School and Virginia Institute of Marine Science.
“We are accelerating at a high rate compared to a lot of the rest of the country, but that rate hasn't been changing, really,” said Molly Mitchell, an assistant research professor. “It's been a pretty consistent rate.”
She said that can give local leaders more confidence in using current data for long-term planning on adapting infrastructure to rising waters.
VIMS started releasing the annual report card in 2018 to assess how coastal cities across the U.S. are experiencing sea level rise.
“You hear about sea level changes that are kind of a global rate, but what's happening at any given place is a combination of a lot of different factors,” Mitchell said.
For example, southeastern Virginia is sinking twice as fast as sea level is rising, compounding the issue. That’s largely because of the land naturally adjusting to the retreat of ancient glaciers, as well as humans pulling groundwater from the Potomac aquifer.
In other areas, the opposite is happening because of cities’ locations along tectonic plates or differing ocean currents, Mitchell said.
The researchers used data from tide gauges in three dozen communities along the West, East and Gulf coasts, including Yorktown and Norfolk.
Most locations showed continued acceleration. That includes Hampton Roads, where water levels crept up by about 5.6 millimeters each year over the past five years.
The Gulf Coast is experiencing the fastest acceleration, such as in Texas and Louisiana.
On the East Coast, Norfolk has long been a hotspot. But Mitchell said one interesting trend is happening farther south.
Tidal data suggests the hotspot is moving south with high rates of acceleration in areas such as Charleston, South Carolina and Wilmington, North Carolina.
“They're still lower than Norfolk, but maybe they're starting to slowly catch up,” Mitchell said.
One likely reason is that the southern coasts are disproportionately impacted by the melting of the Greenland ice sheet because of a complex dynamic involving ocean temperatures and currents.
If the next 30 years are similar to the past few decades, Mitchell said Hampton Roads can expect a little more than 1.5 feet of sea level rise by 2050, as compared to 1992 levels. Some global climate models put that number closer to 3 feet.
Mitchell said though it sounds insignificant, she compares the situation to standing on a beach and trying to avoid getting your feet wet.
“You look out and see a wave coming in that's a foot higher than the other waves,” she said. “You find you actually have to back up probably like 10 feet even though that wave is just a foot higher. What we have in Virginia is a lot of really low, flat land. So a small change in the height of the water can mean a lot more flooding.”
